Surface pattern stylus board

ABSTRACT

A stylus board for a printing machine prints from styli formed on the face of the board. The printing styli can be shaped by etching or deposition to give accurate stylus shapes in a variety of patterns. The board may be curved or folded to elevate the styli at the printing station.

United States Patent [1 Lamb [ Nov. 13, 1973 SURFACE PATTERN STYLUSBOARD [75] Inventor: Reginald T. Lamb, Mountain View,

Calif.

[73] Assignee: Bausch & Lomb, Incorporated,

Rochester, N.Y.

22 Filed: May 6,1971

[21] Appl. No.: 140,824

[52] US. Cl. 197/1 R, 346/139 A v[51] Int. Cl B41j 3/50 [58] Field ofSearch 197/1; 346/74 E,

346/74 ES, 74 M, 74 S, 74 SB, 74 CH, 139, 76, 141; 101/93 C Sakurai eta1 197/1 X 3,161,457 12/1964 Schroeder et a1 197/1 X 3,108,534 10/1963Preisinger 101/93 C 3,112,693 12/1963 Williams 197/1 X 3,277,818 10/1966Cone 197/1 3,190,957 6/1965 Foley et a1..... 197/1 X 3,174,427 3/1965Taylor 197/1 X Primary Examiner-Robert E. Pulfrey Assistant Examiner-R.T. Rader Attorney-Frank C. Parker and Bernard D. Bogdon [57] ABSTRACT Astylus board for a printing machine prints from styli formed on the faceof the board. The printing styli can be shaped by etching or depositionto give accurate 17 Claims, 24 Drawing Figures PAIENIEMuH 3 I975 3; 771.634

sum 1 or 7 FIG 1 INVENTOR. REGINALD T. LAMB ATTORNEYS v PAIENIEDunv 131975 SHEET 3 OF 7 IN VEN TOR. REGINALD T. LAMB ATTORN YS OE, m NnSQQQ WIISQmQJ W DT i w in l A a T N? m I I II I 7- v3 I v I SHEET I 0F 7 e0 owmm 3 3 mm m o u u w u u u u u u m I I; m? N w lql I n.

PAIENTEDIIIIY 13 I973 I I I l I I I II I II I lmwb II. I m: I II? m E wII III PAIENIEnmm Ian 3.771.834 SHEET 5 OF 7 FIG 8 20l FlG 12A INVENTOR.REGINALD T. LAMB @jJW ATTORNEYS PATENTEB I07 1 3 I973 SHEET 5 UF 7 FIG18 FIG 16 FIG .17

INVENTOR. REGINALD T. LAMB ATTORNEYS FIG 19 Y PMENIEUIIIV 13 I975 SHEET7 OF 7 FIG 23 INVENTOR. REGINALD T. LAMB BY w ,WW-

ATTORNEYS SURFACE PATTERN STYLUS BOARD The present invention relates toa printing machine of the kind which utilizes a plurality of individualstyli linearly aligned at a printing station for producingelectro'static, thermal or electro-sensitive printing of a printingmedium which is moved in increments, or steps, or continuously over thestyli at the printing station.

The present invention relates particularly to a method of formingindividual styli on a face of a stylus board for such a printing machineand to a method of and apparatus for using the stylus board so thatprinting can be done from the face of the board.

The stylus board of the present invention has a particular use in aprinter of the kind disclosed in my pending U.S. Application Ser. No.877,128 filed Nov. 17, 1969 and assigned to the same assignee as thisapplication.

The single most important technical factor in the production and use ofelectrostatic, thermal and electrosensitive printers is the printinghead which marks the paper or other medium to be printed.

The head design affects the aesthetics of the print out. That is, thehead design affects the resolution, the sharpness and the dot shape forprint out. The head design also affects the cost and reliability of theprinter.

In a printing machine of the kind in which this invention relates, thestyli or electrodes for energizing or producing a charge on selectedareas of the recording medium are arranged in a line at a printingstation. The recording medium is transported in strip form past theprinting station. The image is progressively built up by successiveapplication of voltage to the styli or electrodes as the strip is movedpast the printing station.

Individual styli or electrodes used in printing machines of this kindare quite small. The individual styli may have an area in contact withthe proper which is 0.010 inch by 0.010 inch, more or less.

By suitable control of the energization or firing of such styli orelectrodes, almost any pattern of surface image can be produced.Numbers, letters, graphs, charts and drawings can be produced.

For electrostatic printing, the assignee of this application has in thepast used a printed circuit board (in a machine of the kind disclosed inthe above noted pending U.S. Application Ser. No. 877,128) withconductor traces electro-formed up to mils by 5 mils at the end of thetraces (at the edge of the board) where the traces or styli touch thepaper. Other manufacturers have used wires. Still other manufacturershave used both printed circuit boards and wires. In the prior art thepresent commercial machines all use the end of the styli to print, andthe shape of the dots and the overall pattern is limited by theprocesses used. All of these prior art boards have been relativelyexpensive.

It is a primary object of the present invention to fabricate a stylusboard for electrostatic, thermal, and electro-sensitive printing whereinthe face of the board, rather than the edge of the board contacts thepaper.

It is a related object to shape thepr'inting styli by etching ordeposition to give more accurate shapes in a greater variety of patternsthan is possible with the prior art method of fabricating stylus boards.

It is another object of the present invention to arrange the styli intwo rows with the individual styli in one row offset or staggered, withrespect to the individual styli in the other row. The individual stylican be made oversized with respect to the lateral spacing between styliin the opposite row and with respect to the spacing between the two rowsso that the styli can print a solid line in both horizontal and verticaldirections on the recording medium. It is a related and specific objectof the present invention to construct such a dual row.

of staggered styli that will print dot matrix alpha numerics in a waythat the alpha numerics do not show a dot pattern.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show preferredembodiments of the present invention and the principles thereof and whatare now considered to be the best modes contemplated for applying theseprinciples. Other embodiments of the invention embodying the sameor'equivalent principles may be used and structural changes may be madeas desired by those skilled in the art without departing from thepresent invention and the purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side elevationview, partially broken away to show the details of construction, of aprinting machine constructed in accordance with one embodiment of thepresent invention;

FIG. 2 is a block diagram showing in diagramatic form the way in whichthe elements of the printing machine shown in FIG. 1 are operativelyassociated;

FIG. 3 is a front elevation view showing the way in which styluselectrodes and segment electrodes may be positioned on opposite sides ofthe recording medium (for electrodes and segments positioned on the sameside of the recording medium see FIGS. 21 and 22);

FIG. 4 is a diagrammatic view illustrating the way in which the totalvoltage for energizing the electrodes is divided between the styluselectrodes and the segment electrodes;

FIG. 5 is a top plan view, partially broken away, of a stylus boardconstructed in accordance with one embodiment of the present invention;

FIG. 6 is a fragmentary enlarged view of the portion of the stylus boardshown encircled by the arrows 6-6 in FIG. 5 and shows details of how thestylus electrodes are accessed from different sides of the stylus board;

FIG. 7 is a fragmentary enlarged plan view of a portion of FIG. 6illustrating details of the way in which the traces are connected to theconductors on the opposite sides of the board;

FIG. 8 is a fragmentary cross-sectional view taken along the lines andin the direction indicated by the arrows 88 in FIG. 7;

FIG. 9 is a fragmentary enlarged and elevation view, in cross-section,showing a stylus board folded in accordance with an embodiment of thepresent invention;

FIG. 10 is a fragmentary perspective view of another embodiment of afolded stylus board constructed in accordance with the presentinvention;

FIG. 1 1 is a fragmentary enlarged end elevation view in cross-sectionillustrating a way in which the folded stylus board of FIG. 10 isassociated with the recording medium;

FIG. 12 is a fragmentary plan view showing how the stylus electrodes maybe formed in two rows and offset, or staggered, in a stylus boardconstructed in accordance with another embodiment of the presentinvention;

FIG. 12A is a plan view of a horizontal line printed with the stylusboard construction shown in FIG.12 and illustrates how a solid line maybe printed with the electrode arrangement shown in FIG.12.

FIG. 13 is a fragmentary top plan view of a part of the stylus boardshown in FIG. 12;

FIG. 14 is an end elevation view cross-section view taken along the lineand in the direction indicated by the arrows 1414 in FIG. 13; I

FIG. 15 is a fragmentary top plan view of a part of a stylus board shownin FIG. 12;

FIGS. 16, 17 and 18 are end elevation views in crosssection, takengenerally along the line and in the direction indicated by the arrows18-18 in FIG. 15, showing how the stylus board may be progressivelybuilt up by deposition;

FIG. 19 is a plan view of the alpha numeric character S as printed bythe stylus board shown in FIG. 12; and

FIG. 20 is a view like FIG. 19, showing, for comparison, the samecharacter as printed by a stylus board having a single row of styluselectrodes.

FIG. 21 is a fragmentary elevation view (like FIG. 9) showing anembodiment in which the segments are on the same side of the recordingmedium;

FIG. 22 is a fragmentary top plan view taken along the line and in thedirection of the arrows 2222 in FIG. 21; and

FIG. 23 is a fragmentary perspective view showing an embodiment in whichthe paper is curved at the printing station to define the area overwhich charge transfer takes place.

A printing machine constructed in accordance with one embodiment of thepresent invention is indicated generally by the reference numeral 31 inFIG. 1.

The printing machine 31 includes a base frame 33 (which may be acasting) and a cover 35.

The printing machine includes a printing station 37.

The printing machine illustrated in FIG. 1 is an electrostatic printingmachine and thus includes a toner station 39. t It should be pointedout, however, that the present invention is not limited to electrostaticprinting machines. The present invention is equally applicable for otherprinting machines, such as thermal and electrosensitive printingmachines.

The printing machine includes a drive means 41.

As best shown in FIG. 2 the printing machine 31 also includes a controlmeans indicated generally by the reference numeral '45.

The power supply for the printing machine 31 is indicated generally bythe reference numeral 47 in FIG. 2.

The top cover 39 includes a lid 49 mounted for pivoting movement about apivot 51. The lid 49, when opened, provides access to the storagecompartment 43.

The printing medium in the form of sheet material 52 is transportedthrough the printing machine in strip form, and the material may besupplied by a roll 55 as illustrated in the solid outline in FIG. 2, orfrom a fan folded supply 50 of sheet material located below the storagecompartment as shown by the dashed outline in FIG. 1.

When the sheet 52 is paper, the sheet may have a thin layer ofdielectric material which receives an electrostatic charge at theprinting station 37.

The electrostatic charge is produced on the sheet at the printingstation bycoaction between two rows of electrodes.

As most easily seen in the diagrammatic view of FIG. 4, the printingstation 37 has a lower row of stylus electrodes 61 and an upper row ofsegment electrodes 63. It may also have styli and segments on the sameside of the paper.

The individual stylus electrodes are indicated by the referencecharacters E1 B96 in FIG. 3. These stylus electrodes are shown as linesfor ease of illustration in FIG. 3 but actually have small rectangularor circular shapes at their surfaces presented to the underside of sheet52.

As will .be described in greater detail below, one form of the presentinvention permits the use of electrodes ,of circular shape havingdiameters larger than the distance between printed dots, e.g. 0.015inches on 0.010 centers.

In a specific form of the printing machine of the present invention,there are 10.24 of the stylus electrodes in the row 61 to cover 1024inches of a standard 11 inch wide recording sheet.

In accordance with the present invention, the stylus electrodes aredivided into groups, with the same number of electrodes in each group.Correspondingly numbered and located electrodes in each group areconnected together by a common supply line. Thus, referring to FIG. 3,the first electrode E1 in each group is connected in parallel with thefirst electrode E1 in each other group by a common supply line orhighway H1, and the fifth electrode E5 in each group is connected by acommon supply line or highway H5. Highway H1 thus connects electrodesEl, E33, E65 and so on. (counting the electrodes consecutively from theleft side as shown in FIG. 3) and highway H5 connects electrodes E5,E37, E69 and so on.

The row of stylus electrodes 61 also has each group further divided intoan odd block and even block as illustrated in FIG. 3. Each block has thesame number of electrodes.

As will be described in greater detail below in the description oftheoperation of the printing machine, the control means 45 include aregister which loads one block at a time. The control means then firethat block after loading and while the data register for the next blockis loading.

This manner of firing a block of stylus electrodes and also the mannerin which the row 63 of segment, or back-up, electrodes is associatedwith the block of stylus electrodes is effective to cause only thestylus electrodes to fire that are required for charging a selected areaon the sheet, even though the common highway supplies voltage to acorresponding electrode in every group. 1

As also best shown in FIG. 3, the row of segment or back-up electrodes63 include individual segment electrodes B0, B1, B3, etc., aligned in aneven, odd, even, odd, etc., manner as illustrated in FIG. 3.

Each segment electrode has a length equal to the length of a block ofstylus electrodes.

The row 63 of segment electrodes may be offset as illustrated in FIG. 3so that each block has two segment electrodes associated with thatblock. Thus, the first odd block of the first group of stylus electrodeshas even segment electrode B0 and odd segment electrode B1 associatedwith that block. The even block of stylus electrodes of the first grouphas the first odd segment electrode B1 and the second even electrode B2associated with that second block. The third odd block of styluselectrodes in the second group has the second even segment electrode B2and the third odd segment electrode B3 associated with that third block.

A certain threshold voltage is required to produce a printable charge onthe sheet. One type of coated paper can require a minimum charge ofabout 350 volts for the pigmented particles of the toner to be'attachedto the charged area of the paper. Any charge less than this would not besufficient to pick up a particle from the toner. Any charge greater thanthis would be sufficient to pick up a particle from the toner.

In accordance with the present invention, the required total chargingvoltage is divided between the rows of electrodes, so that the voltagesupplied to any individual stylus electrode is not by itself sufficientto produce a charge above the threshold level, but is sufficient toproduce a charge on the paper when combined with the charge of anenergized andopposed segment electrode. If the stylus electrodes wereindividually connected to the control means (rather than in parallel bythe highways H as described above), it would be possible to energize asingle backup electrode continuously at a set level (rather thansegmented electrodes) and then to fire the individual stylus electrodesby selective energization of the stylus electrodes at greater thanthreshold voltage, e.g. (350-400 v). However, with the parallelconnections through the highways 1-1, the firing of the styluselectrodes is controlled by selective energization of certain ones ofthe segment electrodes.

As shown in FIGS. 2 and 3, the stylus electrodes go from ground to aboutminus 300 volts when energized and the segment electrodes go from groundto about plus 300 volts when energized.

As also shown inFIG. 2, these voltages are supplied by the power supplymeans 47 including the positive high voltage power supply and thenegative high voltage power supply.

In the operation of the printing station 37 as so far described, andwith reference to FIGS. 2 and 3, the input data for the styluselectrodes is fed into a data register 71 of the control means 45 ineither bit serial form, or 16 bit parallel form. The data register 71receives the data for the first odd block of stylus electrodes until theregister for that block is filled. At that time the information is fedin parallel by the data register to the stylus drivers 73, and thestylus drivers fire the first group in response to a signal from theposition select register 75. This energizes the selected individualelectrodes of the first odd block in the first group. Firing the styluselectrodes in parallel increases the speed by the order of magnitude ofthe stylus electrodes in parallel, e.g. I00 styli in parallel would givea 100 fold increase in speed over firing each electrode individually.

At this time the position select register 75 has also signaled thesegment select and drivers 77 to fire the first even segment B0 and thefirst odd segment B1, so that the individual stylus electrodes energizedin the first odd block of the first group are effective to produce thedesired charge on the selected area of the sheet above the first oddblock. At this time, no other segment electrodes are energized by thesegment select 77. Even though individual electrodes in the other oddblocks of the other groups of stylus electrodes corresponding to theselected electrodes in the first odd block are also energized, none ofthese other stylus electrodes will be effective to produce a charge onthe paper since none of the other opposed segments are energized.

While the first odd block is firing, the data register for the secondeven block is being filled up. After the first odd block has fired, andafter the data register for the second even block has been filled, theposition select register signals the stylus drivers 73 to fire thesecond even block of stylus electrodes as selected by the informationsupplied from the data register 71, and the position select register 75simultaneously signals the segment selection logic and drivers 77 tofire the first odd segment electrode B1 and the second even segmentelectrode B2 associatedwith the second block of stylus electrodes. -Asdescribed above with reference to the first odd block of styluselectrodes, only the selected electrodes in the selected block areeffective to produce an electrostatic charge on the sheet. While thesecond even block of stylus electrodes are firing, the data register forthe third odd block of stylus electrodes in the second group is filling.After firing of the second even block is completed, the firing of thethird block begins; and the filling of the data for the fourth evenblock also begins. On the firing of the third block of styluselectrodes, the second even segment electrode 132 and the third oddsegment electrode B3 are energized by the segment select and driver 77.This process is repeated down the length of the two rows ,of electrodesuntil all of the stylus electrodes selected for producing a charge onthe sheet have been fired.

After the firing of the rows of stylus electrodes has been completed,the position select register 75 signals the motor control 79 to step thesheet 52 one step in preparation for the next firing of the row ofelectrodes.

The data fed into the data register is supplied from a logic circuitwhich is energized at a relatively low voltage, e.g. plus five volts asillustrated in FIG. 2.

The logic circuit and the greater part of the control means 45 arecontained on printed circuit cards not shown, carried in a card cage 83located behind the storage compartment 43 for the supply of sheetmaterial.

The drive means 41 for transporting the sheet 52 through the printingmachine include a drive roller 121 and a squeegee roller 123.

The squeegee roller 123 is directly connected for drive by the motor 125(FIG. 2). Alternatively, the squeegee roller may be driven by frictionfrom the paper. The drive roller 121 and the toner roller are drivenfrom the squeegee roller by gears. The force with which the squeegeeroller and drive roller 121 are engaged causes the drive roller to pullthe sheet 52 through the printing machine by a winching action.

The toner roller 105 picks up toner from the trough and applies thattoner to the underside of the sheet 52. The toner roller 105 is partlyimmersed in toner liquid 105 containing the pigment and particles, e.g.carbon particles in a colloidal suspension. The toner roller has asurface which distributes the particles evenly across the surface of thesheet 52 so that the particles can be attracted to the areas of thesheet having the electrostatic charges.

Thus, as the sheet 52 passes through the toner station 39, apredetermined image is reproduced as represented by the figures S inFIGS. 19 and 20. The width of each individual dot represents the widthof an individual stylus electrode, and the distance between the centersof two immediately adjacent vertical dots represents the amount that thesheet has advanced on each advancement through the printing station.

In the machine shown in FIG. 1 the row 63 of segment electrodes may beattached to the underside of the lid 49. Alternatively, they might beformed on the stylus board, as shown for example in FIG. 21.

In accordance with the present invention the stylus electrodes areformed on the surface of the stylus board 91 rather than on the edge ofthe board.

Different embodiments of the stylus board having stylus electrodesformed on the surface of the board are shown in FIGS. 5 18 of thedrawings.

The stylus electrodes may be presented in a single line, as illustratedin FIGS. 5 11.

The stylus electrodes may also be presented in two or more rows in whichthe stylus electrodes in one row are offset with respect to the styluselectrodes in the other row. This form of the present invention isillustrated in FIGS. 12, 12A, l3, l4 and 15-18.

In either embodiment the stylus electrodes may be formed by a photoetching process or by a combined photo etching and deposition process(as illustrated in FIGS. 15-18) or by other suitable fabricationprocesses, such as, for example, thin/thick film techniques; buryingconductors in ceramic and adding styli and traces after potting theceramic; metal coating channels in ceramic blanks or squeeging metal insuch channels and lapping true before adding traces and styli; andcuring green blanks having molded in holes and channels and then addingmetal.

In any event, the principle of the present invention (forming the styluselectrodes or pads on the face or surface of the stylus board) providesstructural, operational and cost benefits which have not previously beenattainable in printing machines of the kind to which this inventionrelates.

Regardless of the specific process used, the shapes of the styluselectrodes can be very accurately made on the surface of the board. Thespacing and arrangement of the stylus electrodes can also be veryaccurately controlled.

In the embodiment of the invention having two rows of offset orstaggered stylus electrodes, forming the stylus electrodes on the faceor surface of the stylus board produces a perfect staggered pattern withno cumulative error in the stagger. That is, each stylus electrode inone row is perfectly registered between two stylus electrodes in theopposite row, whether at the beginning of the row, the middle of the rowor at the end of the row. This is possible because both rows of styluselectrodes are exposed from one transparency, in the photo-etchingprocess, and this gives perfect registration. Obtaining satisfactoryregistration for two rows of stylus electrodes has been a problem in theprior art. In the prior art it has been necessary to laminate twoseparate stylus boards (having edge formed stylus electrodes) together.Because of the small size of the electrodes, the small spacing betweenadjacent electrodes and the limitations .of the manufacturing processesavailable for forming edge mounted electrodes, attempts to laminate twoboards together often resulted in unacceptable registration at variouspoints along the rows of electrodes. That is, placing the styluselectrodes in registration at one end of the board might result in acomplete lack of registration at the other end of the board.

An embodiment of the present invention in which the stylus electrodesare aligned in a single row as illustrated in FIGS. 5, 6, 7 and 8.

FIG. 5 is a plan view of a stylus board 91, and FIG. 6 is a fragmentaryenlarged plan view of the portion of the stylus board 91 shown encircledby the arrows 66 in FIG. 5. FIGS. 7 and 8 are additional fragmentaryenlarged views showing structural features in larger detail than FIGS. 5and 6.

The individual stylus electrodes may be formed with a rcctangular shapeas shown in FIGS. 5 and 6, or with circular dot shapes, as shown inFIGS. 7 and 8 or with some other pad configuration if desired.

As best illustrated in FIGS. 6 and 7, each stylus electrode E1 throughE65 in FIG. 6 is connected by its own conductor trace (T1 T65 in FIG. 6)to a terminal point on the stylus board located at varying distancs fromthe row of stylus electrodes.

Thus, stylus electrode E1 is connected through a conudctor trace T1 to apad 95 having a plated through hole 97. The plated through hole 97connects with a highway H1 on the opposite side of the board. The platedthrough hole 97 thus serves as a terminal point for the traceTl and aconnection to the electrical conductor (the highway H1) on the oppositeside of the board.

Each stylus electrode is similarly ocnnectcd to a related highwayconductor on the opposite side of the board by a pad 95 and a platedthrough hole 97.

The highway H1 through H32 are in turn connected to plug-in connectorson a side edge of the stylus board 91 and the plug-in connectors connectthe stylus board to the stylus drivers 73 (FIG. 2).

As best illustrated in FIG. 8 each stylus electrode or pad is raisedslightly (e.g. k to 5 mils) above the surface of the conductor trace.The difference in height between the stylus pad or electrode and thetrace surface gives preferential charge transfer from the stylus pad tothe paper over the transfer from the trace to the paper. An insulatinglayer over the trace may be added to increase the preferentialdifferential.

Another feature of the present invention, as well illustrated in FIG. 6,is the fact that the stylus electrode or pad can be accessed by traceson alternate sides of the board. This doubles the space available foreach trace. This makes the traces much easier to manufacture. Thus, asillustrated in FIG. 6, the stylus electrodes E1, E3, E5, etc., areaccessed from one side of the board by the corresponding traces, T1, T2,T3, etc., and the stylus electrodes, E2, E4, E6 etc., are accessed bytraces T2, T4, T6, etc.

The traces are etched (or deposited) on a relatively thin substrate(e.g. 0.002 inch to 0.10 inch) and the plated through holes 95 can belarger and therefore easier to drill and to plate than in the prior artstylus board constructions.

The stylus heads may be plated to build up the height as illustrated inFIG. 8. The stylus electrodes or pads may also be made by using thickmetal and etching down the conductor traces to give the height(thickness) differential.

The stylus boards may be fabricated from blanks with metal on bothsides. The larger holes and thinner substrates permit drilling many moreboards simultaneously than has been possible in the prior art. Thelarger tolerances on the hole locations also reduces cost.

The stylus boards 91 are etched and plated in the flat, as illustratedin FIG. 5.

As illustrated in FIGS. 9, and 11 the stylus boards may then be formedaround a core to a final shape as shown in FIGS. 9, 10, and 11. In thisform of the invention, the stylus electrodes are placed on the peripheryof the curve (which typically may be Va inch radius).

FIG. 12 shows an embodiment of the invention in which the styluselectrodes are arranged in two rows with the electrodes in one rowoffset with respect to the electrodes in the other row.

FIG. 12A illustrates a possible print out from a dual row of styluselectrodes having the relative dimensions and spacings illustrated inFIG. 12. By using circular shaped electrodes or pads having diameterslarger than the lateral spacings between the adjacent electrodes it ispossible to print a horizontal line with full overlap for a very darktrace as illustrated in FIG. 12A. In FIG. 12A the printed dots 201 arenumbered 1, 2, 3, 4, 5, 6 to correspond to the electrodes E1 through E6which print these dots.

The row printing sequence for accomplishing the print out shown in FIG.12A would be as follows:

1. first row odd 2. second row odd 3. third row odd first row even 4.fourth row odd second row even This staggered pattern requires delayingprinting of even styli for two full papaer steps. A two line buffermemory is used for this. Two steps after printing the first line, itsdot images are aligned between the even stylus pads and at that time thefirst line of even dots is printed.

- The arrangement of stylus electrodes shown in FIG. 12 also permitsprinting solid black in a vertical direction, as illustrated by theprint out of the letter Sin FIG. 19. In this regard, it should be notedthat the incremental advancement of the paper sheet is less than thediameter of the circular shaped stylus electrodes. In a typicalconstruction, the diameter of each stylus electrode would be 0.015 inch,and distance between the lines of centers of adjacent electrodes in onerow would be 0.010 inch and the distance between the center lines of thetwo rows would be 0.010 inch. The paper would be advanced 0.005 incheson each incremental advancement.

FIGS. 13 and 14 are fragmentary enlarged views showing how the dual row,staggered stylus electrode arrangement can be fabricated. In this case,the board 91 can be a Kapton or epoxy composition. The conductor tracesT1, T2 etc. can be copper photo-etched. The stylus electrodes or padsEl, E2 etc. can be platedup nickel 0.001 inch to 0.005 inch thick. Theholes 97 are plated through. And the highways such as H2. can bephoto-etched copper.

An alternative would be to photo. etch a pattern to a certain thickness,such as 4 mils, then to put a resist on the areas of the styluselectrodes or pads El, E2 etc., and to photo etch the remainder back to1 A mils, leaving the pads 4 mils thick.

Another alternative would be to make a ceramic substrate with thehighways and plated through holes metalized and then to metalize thestylus electrode pads and photo etch a pattern or to deposit the padsand the conductor trace pattern.

FIGS. 15-18 show a thick film fabrication technique which may be used.The first step of the process is to photo etch a copper highway patternon the substrate of the board 91. The next step is to deposit adielectric 203 with holes at 205. The next step is to deposit theconductor trace (T1, T2, etc.) pattern contacting the highways throughthe holes 205 in the dielectric 203. As a last step the pads E1, E2etc., are built up by platingor vacuum deposition.

FIGs. 21 and 22 show an embodiment of the invention in which the segmentelectrodes and stylus electrodes are both disposed on the same side ofthe recording medium. I I The combination of the charges impressed onthe dielectric layer 221 by the segment electrodes 23 and those styluselectrodes 61 which are energized causes an image to be formed in thesame manner as described in the other embodiments of this invention.

The embodiment shown in FIGS. 21 and 22 also incorporates longerons 223which extend along the back face of the board 91 parallel to thehighways, such as the-H1 shown in FIG. 21. The longerons are usedprimarily as stiffeners to cause the board 91 to bent at certainpositions and certain angles with respect to the styli 61. Thus, theboard 91 bends on the fold lines 225 (See FIG. 22) between longerons 223and the first highway III to present the styli and segments to therecording medium in a relatively flat plane.

It should also be noted that the longeron 223 can also be used oncapacitive couplings to be pulsed and to correct capacitive couplingsdeveloped between relatively long traces of adjacent styli. In thiscase, a pulse on a longeron 223 is capacitively coupled to all thestyli, and this pulse is selectively accepted by the styli. That is, theunselected styli couple to the pulse and the selected or energized styliare less affected because the selected styli are shorted to ground.

FIG. 23 shows an embodiment of the invention in which the board 91 isheld completely flat and the paper of the recording medium 52 is curvedat the printing station.

In this construction the segment board 77B and segments 63 may also becurved as illustrated in Fig. 23.

This construction has several advantages.

Curving the paper as illustrated minimizes the possibility of a chargetransfer from a trace, such as T1, to the paper because the paper iskept well spaced from the traces by reason of its curvature.

The stylus board 91 can be supported by a resilient backing 229 at theprinting station. This resilient backing minimizes uneven levels of theline of stylus electrodes along the length of the line, and thus insuresthat all stylus electrodes aremaintained in good contact with therecording medium.

Curving the paper in this manner can also be an advantage in that thepaper may be permitted to follow its normal curvature as it is lead offa roll with the dielectric layer inside.

The segment board 77B and segments 63 are held in position by a core 227as illustrated.

While I have illustrated and described the preferred embodiments of myinvention, it is to be understood that these are capable of variationand modification, and I therefore do not wish to be limited to theprecise details set forth, but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

1. An electrode board for a printing machine of the kind in which datais printed on sheet material at a printing station by electrodes whichare arranged in a line at the printing station and which are selectivelyenergized to produce electrostatic charges on certain areas of the sheetmaterial transported in a strip form through the printing station, saidelectrode board comprising; a board member of dielectric materialshaving first and second faces disposed on opposite sides of the board; aplurality of stylus electrodes disposed on said first face and along onepart of said board member, and arranged to provide closely spacedelectrodes for producing electrostatic charges on the sheet materialpassing over said one part of the board member, said electrodes beingdivided into groups along the length of said one part of the boardmember with the same number of electrodes in each group; a plurality ofterminal points on said first face; a lead connected to each electrodeand extending from said one part of the board member and terminating atone of said terminal points, each lead for each electrode in any onegroup having a different length than any lead of any other electrode inthat group whereby the leads terminate at different distances from onesaid part of the board member, each lead for each correspondingelectrode in each group having a length for readily connecting thecorresponding electrodes in each group by a common supply line; aplurality of supply lines corresponding in number to the number ofelectrodes in each group mounted on said second face of the board memberwith each supply line aligned with the terminal point of one set ofleads extending from said one part of the board member; and connectionmeans extending through the board member for providing an electricalconnection between such supply lines and the ends of the leads toconnect each electrode in each group with the corresponding electrode ineach other group by a common supply line on said second face of theboard member.

2. The electrode board of claim 1 wherein less than all of the styluselectrodes are connected to leads extending towards one edge of said oneside of said board member, and the remaining electrodes are connected toleads extending towards the opposite edge of said one side of said boardmember, and wherein less than all of said supply lines are disposed tobe connected to said leads connected to said less than all of saidelectrodes, and the remainder of said supply lines are disposed to beconnected to the leads connected to said remaining electrodes.

3. The electrode board as defined in claim 1 wherein said board memberincludes a plurality of holes through it, and wherein the connectionmeans connecting the leads through the board member with the supply lineof the other side of the board member includes electrically conductivecoatings lining said holes.

4. The electrode board as defined in claim 1 wherein the supply linesterminate at one edge of the board member and wherein plug-in connectorsare attached to the ends of the entire electrode board to be quicklyplugged into a control circuit for controlling energization ofelectrodes in each of the groups.

5. A printing machine of the kind in which images are printed on sheetmaterial at a printing station by electrostatically charging selectedareas of the sheet at the printing station to attach pigmented particlesto the electrostatically charged areas, comprising a first row ofelectrodes at the printing station linearly aligned on one side of thesheet, a second row of electrodes at the printing station linearlyaligned on an opposite side of the sheet, control means supply voltagesto selected ones of the electrodes in the first and second rows forproducing an electrostatic charge on the sheet including divider meansfor dividing the voltages between the two rows of electrodes in a mannersuch that a voltage supplied to any individual electrode in either thefirst or the second row is less than that required to produce the chargebut is sufficient to produce the charge when added to the voltage on anopposed electrode in the opposite row, wherein the electrodes in thefirst row are stylus electrodes disposed on the face of a folded stylusboard and are divided into groups having the same number of electrodesin each group and having correspondingly located and numbered electrodesin each group connected by a common supply line on the stylus board,each of the stylus electrode groups being further divided into twoblocks with the first half of the electrodes in the group being locatedin an odd numbered block and the second half of the electrodes in thegroup being located in an even numbered block, and wherein theelectrodes in the second now are segment electrodes with the length ofeach segment electrode being equal to the length along the stylus row ofelectrodes occupied by one block of thestylus electrodes, the row ofsegment electrodes being offset with respect to the stylus electrodes in9 manner such that each block of stylus electrodes has one even numberedand one odd numbered segment electrode spanning the length of the blockof stylus electrodes with one-half of the length of the even numberedsegment electrode and one-half of the length of the odd numbered segmentelectrode extending beyond the ends of the block of stylus electrodes.

6. A stylus board for printing machine of the kind in which data isprinted on a recording medium at a printing station by styli which arearranged in a line 'at the printing station and which are selectivelyenergized to produce images on the recording medium, said stylus boardcomprising a board member of dielectric materials having first andsecond faces disposed on opposite sides of the board; a plurality ofindividual styli disposed on said first face and along one part of saidboard member and arranged to extend outwardly from said first facetowards said recording medium as individual raised surfaces; a pluralityof terminal points on said first face; a conductor connected to each ofsaid styli and extending from its respective styli to one of saidterminal points, a plurality of supply lines disposed on said secondface of the board member with each supply line aligned with at least oneof said terminal points; and connection means extending through theboard member for providing an electrical connection between the supplyline aligned with one terminal point and the conductor extending to thesame terminal point.

7. A stylus board as defined in claim 6 wherein the styli are disposedon the face of the board spaced from and intermediate opposite edges ofthe board and the board is made of material such that it may be foldedto locate the styli at the printing station closer than said conductorsto said recording medium.

8. A stylus board as defined in claim 7 wherein the styli are located onsaid face adjacent to and aligned with each other and the board isfolded on an imaginary line drawn through adjacent styli to place thestyli on the periphery of the fold.

9. A stylus board as defined in claim 6 wherein the styli are formed ona portion of the face of the board spaced from and intermediate oppositeedges of the board, and less than all of the styli are connected toconductors extending from said intermediate portion towards one of saidedges, and the remaining styli are connected to conductors extendingfrom said intermediate portion to the other of said edges.

10. A stylus board as defined in claim 6 wherein the styli are spacedapart and aligned in two adjacent, spaced apart rows and the styli inone row are staggered with respect to the styli in the other row.

11. A stylus board as defined in claim 10 wherein the styli in each roware larger than the space between the styli in the opposite row so thatthe styli can be energized to print a solid line.

12. A stylus board as defined in claim 11 wherein the space between theadjacent rows is less than the width to terminal points in one part ofthe board and the styli in the other row are accessed by conductorsextending to terminal points in an opposite part of the board.

16. A stylus board as defined in claim 6 wherein the board is curved sothat the styli are linearly aligned on the outside periphery of thecurve.

17. A stylus board as defined in claim 6 including segment electrodesformed on the same face of the board as the styli, said segmentelectrodes being aligned adjacent to and spaced from the styli.

.UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I Patent No. 3,771,631+ 1 Dated November 13, 73 inventor) I'ieginald '1. Lamb I It iscertified that error appears' in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 37, "proper" should read paper Column h, line 21,"10.21;" should 'read 102i;

Column 1;, line 22, "102A." should read 10.2L

Column 3, line 30, "ocnnected should read connected Column 10, line 25,"bent" should read bend I Column 12, line 6, "supply" should readsupplying Column 12, line 27, "now" should read row 7 Column 12, line30, "thestylus" should read the stylus ajolwnn' 12, line 32, "9" shouldread Signed and sealed this 21st day of May 1971;..

(SEAL) Attest: I

L' ilDl-IARD I-LFIJSTGHEERJR. G. I 'lAR-SHALL DAMN Attesting Officer I vCommissioner of Patents FORM P0-105O (10-69) USCOMM DC 6037645" 12 u.s.aovnrmru-r manna omc: nu o-su-su,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent v DatedNovember 13, 1973 inventofls) Reginald '1. Lamb It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 37, proper" should read paper Column LL, line 21,"10.22;" should reed 102i} Column 2;, line 22, "102E" should read 10.21

Column 8, line 30, "connected" should read connected Column 10, line 25,"bent" should read bend I Column 12, line 6, "supply" should read suoplying Column 12, line 27, "now" should read row Column 12, line '30,"thestylus" should read the stylus Uolumn' 12, line 32, "9" should reada Signed and sealed this 21st day of May 1971p.

(SEAL) Attest:

Attesting Officer Commissioner of Patents FORM PO-1050 USCOMM-DC60376-P69 fl 0.5. GOVERNMENT PRINTING OFFICE: I9, O-JSG'SJI,

1. An electrode board for a printing machine of the kind in which datais printed on sheet material at a printing station by electrodes whichare arranged in a line at the printing station and which are selectivelyenergized to produce electrostatic charges on certain areas of the sheetmaterial transported in a strip form through the printing station, saidelectrode board comprising; a board member of dielectric materialshaving first and second faces disposed on opposite sides of the board; aplurality of stylus electrodes disposed on said first face and along onepart of said board member, and arranged to provide closely spacedelectrodes for producing electrostatic charges on the sheet materialpassing over said one part of the board member, said electrodes beingdivided into groups along the length of said one part of the boardmember with the same number of electrodes in each group; a plurality ofterminal points on said first face; a lead connected to each electrodeand extending from said one part of the board member and terminating atone of said terminal points, each lead for each electrode in any onegroup having a different length than any lead of any other electrode inthat group whereby the leads terminate at different distances from onesaid part of the board member, each lead for each correspondingelectrode in each group having a length for readily connecting thecorresponding electrodes in each group by a common supply line; aplurality of supply lines corresponding in number to the number ofelectrodes in each group mounted on said second face of the board memberwith each supply line aligned with the terminal point of one set ofleads extending from said one part of the board member; and connectionmeans extending through the board member for providing an electricalconnection between such supply lines and the ends of the leads toconnect each electrode in each group with the corresponding electrode ineach other group by a common supply line on said second face of theboard member.
 2. The electrode board of claim 1 wherein less than all ofthe stylus electrodes are connected to leads extending towards one edgeof said one side of said board member, and the remaining electrodes areconnected to leads extending towards the opposite edge of said one sideof said board member, and wherein less than all of said supply lines aredisposed to be connected to said leads connected to said less than allof said electrodes, and the remainder of said supply lines are disposedto be connected to the leads connected to said remaining electrodes. 3.The electrode board as defined in claim 1 wherein said board memberincludes a plurality of holes through it, and wherein the connectionmeans connecting the leads through the board member with the supply lineof the other side of the board member includes electrically conductivecoatings lining said holes.
 4. The electrode board as defined in claim 1wherein the supply lines terminate at one edge of the board member andwherein plug-in connectors are attached to the ends of the entireelectrode board to be quickly plugged into a control circuit forcontrolling energization of electrodes in each of the groups.
 5. Aprinting machine of the kind in which images are printed on sheetmaterial at a printing station by electrostatically charging selectedareas of the sheet at the printing station to attach pigmented particlesto the electrostatically charged areas, comprising a first row ofelectrodes at the printing station linearly aligned on one side of thesheet, a second row of electrodes at the printing station linearlyaligned on an opposite side of the sheet, control means supply voltagesto selected ones of the electrodes in the first and second rows forproducing an electrostatic charge on the sheet including divider meansfor dividing the voltages between the two rows of electrodes in a mannersuch that a voltage supplied to any individual electrode in either thefirst or the second row is less than that required to produce the chargebut is sufficient to produce the charge when added to the voltage on anopposed electrode in the opposite row, wherein the electrodes in thefirst row are stylus electrodes disposed on the face of a folded stylusboard and are divided into groups having the same number of electrodesin each group and having correspondingly located and numbered electrodesin each group connected by a common supply line on the stylus board,each of the stylus electrode groups being further divided into twoblocks with the first half of the electrodes in the group being locatedin an odd numbered bloCk and the second half of the electrodes in thegroup being located in an even numbered block, and wherein theelectrodes in the second now are segment electrodes with the length ofeach segment electrode being equal to the length along the stylus row ofelectrodes occupied by one block of thestylus electrodes, the row ofsegment electrodes being offset with respect to the stylus electrodes in9 manner such that each block of stylus electrodes has one even numberedand one odd numbered segment electrode spanning the length of the blockof stylus electrodes with one-half of the length of the even numberedsegment electrode and one-half of the length of the odd numbered segmentelectrode extending beyond the ends of the block of stylus electrodes.6. A stylus board for printing machine of the kind in which data isprinted on a recording medium at a printing station by styli which arearranged in a line at the printing station and which are selectivelyenergized to produce images on the recording medium, said stylus boardcomprising a board member of dielectric materials having first andsecond faces disposed on opposite sides of the board; a plurality ofindividual styli disposed on said first face and along one part of saidboard member and arranged to extend outwardly from said first facetowards said recording medium as individual raised surfaces; a pluralityof terminal points on said first face; a conductor connected to each ofsaid styli and extending from its respective styli to one of saidterminal points, a plurality of supply lines disposed on said secondface of the board member with each supply line aligned with at least oneof said terminal points; and connection means extending through theboard member for providing an electrical connection between the supplyline aligned with one terminal point and the conductor extending to thesame terminal point.
 7. A stylus board as defined in claim 6 wherein thestyli are disposed on the face of the board spaced from and intermediateopposite edges of the board and the board is made of material such thatit may be folded to locate the styli at the printing station closer thansaid conductors to said recording medium.
 8. A stylus board as definedin claim 7 wherein the styli are located on said face adjacent to andaligned with each other and the board is folded on an imaginary linedrawn through adjacent styli to place the styli on the periphery of thefold.
 9. A stylus board as defined in claim 6 wherein the styli areformed on a portion of the face of the board spaced from andintermediate opposite edges of the board, and less than all of the styliare connected to conductors extending from said intermediate portiontowards one of said edges, and the remaining styli are connected toconductors extending from said intermediate portion to the other of saidedges.
 10. A stylus board as defined in claim 6 wherein the styli arespaced apart and aligned in two adjacent, spaced apart rows and thestyli in one row are staggered with respect to the styli in the otherrow.
 11. A stylus board as defined in claim 10 wherein the styli in eachrow are larger than the space between the styli in the opposite row sothat the styli can be energized to print a solid line.
 12. A stylusboard as defined in claim 11 wherein the space between the adjacent rowsis less than the width of the individual styli so that the styli can beenergized to print solid lines in transversely disposed directions. 13.A stylus board as defined in claim 6 wherein the styli and conductorsare formed as surfaces raised on said board and the styli have a greaterheight above the face of said board than the conductors.
 14. A stylusboard as defined in claim 10 wherein the styli are formed on the boardby a photo-etching process.
 15. A stylus board as defined in claim 10wherein the styli in one row are accessed by conductors extending toterminal points in one part of the board and the styli in the other roware accessed by conduCtors extending to terminal points in an oppositepart of the board.
 16. A stylus board as defined in claim 6 wherein theboard is curved so that the styli are linearly aligned on the outsideperiphery of the curve.
 17. A stylus board as defined in claim 6including segment electrodes formed on the same face of the board as thestyli, said segment electrodes being aligned adjacent to and spaced fromthe styli.